The Department of Labour's case against the Pike River Coal company, its chief executive Peter Whittall and one of its contractors is expected to feature briefly in court.
Today's hearing, in Greymouth District Court, is expected to be procedural and pleas are unlikely to be entered.
The defendants will be represented by their lawyers before a date set for the next court appearance.
Following the deaths of 29 men in explosions in November 2010, the department laid 25 Health and Safety Act charges against the Pike River Coal company, Mr Whittall and drilling company Valley Longwall International.
Mr Whittall is facing 12 charges and says he will defend them. Pike River Coal is facing 10 charges and VLI Drilling three charges.
Each charge carries a maximum penalty of $250,000.
The third phase of the Pike River Royal Commission of Inquiry - looking at what happened at the mine - starts in Greymouth next week.
NZN